code: def test_prune_empty(nest):
      ret = ivy.prune_empty(ivy.copy_nest(nest))
      assert ret == {"b": {"c": [1]}}
  
imports: import copy
  import warnings
  import pytest
  import numpy
  import ivy
label_desc: Use image node_id 21 for calling a global function with example usage: test_prune_empty(nest) without return types